Don't suppose. Analyze. Your real problem is that you analog engineer wants to understand the extent of noise disturbance that is associated with the interconnects and PDN. He first needs to define his problem by deciding for each victim what location in the assembly constitutes his reference. Once that is done, the problem can be solved with analytical tools. An equipotential if it exists somewhere convenient reduces the effort required to get a reasonable answer. Steve On 6/1/2011 4:23 AM, Rajan Hansa wrote: > > Steve, > > The board has many chips including ours and they all have different > current requirement so it won't be correct to consider it > equipotential and if I suppose consider them quasi-equipotential, what > extra things I have to take care while generating s-parameter ?? OR do > you mean to say for quasi-equipotential, separate vdd & gnd > s-parameters will take care our problem ? > > Rajan > > On Wed, Jun 1, 2011 at 4:10 PM, steve weir <weirsi@xxxxxxxxxx > <mailto:weirsi@xxxxxxxxxx>> wrote: > > You have a matrix of current sources attached to a matrix of RLCG > legs, and you want to know the noise voltage that occurs between > different point pairs in that matrix. If the product of the > static and dynamic currents against a section of those legs is > very small, you can treat that region as a quasi- equipotential. > Otherwise you have to treat the point pairs as unique. > > Steve > > > On 6/1/2011 3:29 AM, Rajan Hansa wrote: >> >> Steve, >> >> You are right !! Our analog engineer basically wants to >> see ground bounce w.r.t pcb ground which was not possible with >> single s-parameter but you said that I have to do whole lot more >> than just produce s-parameters between one port inside the >> package and some other virtual port. >> >> Can you help me to understand that why separate s-parameter is >> not sufficient to see ground bounce and what is the right way to >> handle such problems ?? >> Rajan >> >> >> On Wed, Jun 1, 2011 at 3:30 PM, steve weir <weirsi@xxxxxxxxxx >> <mailto:weirsi@xxxxxxxxxx>> wrote: >> >> What it sounds like your analog engineer wants is to be able >> to figure out how much bounce will occur in each plane >> relative to some external reference, such as the PCB Vss >> plane. In order to figure that out, you have to do a whole >> lot more than just produce s-parameters between one port >> inside the package and some other virtual port. Your analog >> engineer needs to be more specific about what he wants to >> figure out. >> >> Steve. >> >> >> On 6/1/2011 1:41 AM, Rajan Hansa wrote: >> >> Guys, >> I have got a request to provide sparameter for one >> package but this time my >> analog engineer wants seperate s-parameter for gnd& >> supply plane. The >> reason he gave is that with single sparameter for vdd& >> gnd plane. He can't >> see gnd noise as s-parameter is generated with gnd as >> reference so it'll >> always be seen as '0' but that problem won't come in >> separate s-parameters >> for gnd& supply planes. >> >> Though the tool I am using has an option to generate >> sparameter with >> reference to some virtual point and I can use that option >> to generate >> separate sparameters for gnd& supply but problem is that >> I have not still >> understood if using separate s-parameter is a right way >> to do things and if >> it's the standard practice in industry. >> >> Experts comments please. >> >> Rajan >> >> >> >> ------------------------------------------------------------------ >> To unsubscribe from si-list: >> si-list-request@xxxxxxxxxxxxx >> <mailto:si-list-request@xxxxxxxxxxxxx> with 'unsubscribe' >> in the Subject field >> >> or to administer your membership from a web page, go to: >> //www.freelists.org/webpage/si-list >> >> For help: >> si-list-request@xxxxxxxxxxxxx >> <mailto:si-list-request@xxxxxxxxxxxxx> with 'help' in the >> Subject field >> >> >> List technical documents are available at: >> http://www.si-list.net <http://www.si-list.net/> >> >> List archives are viewable at: >> //www.freelists.org/archives/si-list >> >> Old (prior to June 6, 2001) list archives are viewable at: >> http://www.qsl.net/wb6tpu >> >> >> >> >> >> -- >> Steve Weir >> IPBLOX, LLC >> 150 N. Center St. #211 >> Reno, NV 89501 >> www.ipblox.com <http://www.ipblox.com/> >> >> (775) 299-4236 Business >> (866) 675-4630 Toll-free >> (707) 780-1951 Fax >> >> >> > > > -- > Steve Weir > IPBLOX, LLC > 150 N. Center St. #211 > Reno, NV 89501 > www.ipblox.com <http://www.ipblox.com/> > > (775) 299-4236 Business > (866) 675-4630 Toll-free > (707) 780-1951 Fax > > > -- Steve Weir IPBLOX, LLC 150 N. Center St. #211 Reno, NV 89501 www.ipblox.com (775) 299-4236 Business (866) 675-4630 Toll-free (707) 780-1951 Fax ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu